Johnson Controls Gmbh

Johnson Service Company

Other

Thomas E Hayes

J Scott Jamieson

Scott L Spence

Russell B Matthews

Jon Harold Bechtel

Martin Coiner Grostick

Robert E Emmons

An apparatus for controlling the speed of a combustion blower motor includes first means for generating an output signal representative of a differential pressure. A second means provides a second signal representative of a desired airflow output of the blower and a summation circuit receives the first signal and the second signal and generates a command signal in response thereto. A power output circuit receives the command signal and responsively provides a regulated level of power to the motor for controlling the speed thereof. The first means may be embodied as a diaphragm-type differential pressure transmitter while the second means may be embodied as an adjustable voltage source or as a source which provides an output signal representative of a temperature.

Furnace draft control with remote control feature

A differential pressure control apparatus includes a switch responsive to a pneumatic differential pressure for signaling the actuation of a blower motor. A signal generating section is provided and controls the speed of a blower for regulating the differential pressure. This section includes first means for sensing a projected light beam and second means for modulating the light beam. The first means and the second means are positionably displaceable one to the other in response to the magnitude of the differential pressure. Two preferred embodiments are disclosed.

Differential pressure control apparatus

A mechanical draft controller integrated in the draft hood of a furnace and coupled to a flue damper is responsive to the draft in the flue for controlling exhaust stack heat loss and eliminating heated room air loss via the draft hood under normal operating conditions. The pressure-sensitive controller is variably positioned as a face damper on a surface of the draft hood and is coupled to the flue damper by means of mechanical linkage. Increasing pressure in the draft hood caused by a reduction in the draft value due to partial flue blockage, large down draft, etc., displaces the pivoted controller resulting in a corresponding opening of the flue damper to re-establish the desired draft value. Similarly, excessive draft causes the displacement of the controller in an opposite direction resulting in flue damper displacement so as to reduce the draft value and exhaust stack heat loss. Between these two operating conditions the controller is variably positioned in the surface of the draft hood so as to block the escape of heated room air via the exhaust stack. A completely blocked flue resulting in an abnormal increase in pressure in the draft hood causes the controller to be further displaced resulting in the further displacement of the flue damper to a nearly completely open position to permit re-establishment of the desired draft value. Another safety feature provides for the breakage of the linkage coupling the draft controller with the flue damper in which case both dampers are automatically opened allowing the system to revert to normal draft hood operation. The draft hood control damper and the flue damper may be utilized in combination with a conventional bimetallic damper positioned downstream from the flue damper in reducing heat loss during burner OFF periods.

Mechanical draft controller with vent damper

A heater vent having a temperature responsive damper such as a bimetallic element is disclosed. A shroud-like structure is positioned to cooperate with the temperature responsive element to close the vent at an elevated temperature and thereby reduce loss of residual heat while permitting the combustion gases to be completely purged from the firebox. For safety, movement of the temperature responsive element is uninhibited in all positions with complete vent closure occurring at ambient temperature and with the damper open during heater burner operation.

Temperature responsive vent damper

The system includes a damper plate equipped with a draft controller or sensing switch and a motor for positioning the damper plate to control the furnace draft. Upon generation of a call-for-heat signal, an initialization signal drives the damper off its closed position. From then on, draft must be sensed by the draft controller switch to complete the cycle to open the damper plate. When the damper plate is fully opened, a fuel and ignition control circuit is energized to supply fuel to the furnace, and an electronic timer is energized to generate a signal which establishes a trial-for-draft period. When the fuel is ignited, the draft will increase and energize the motor to move the damper plate off the fully open position during the trial-for-draft period, and thereafter, the position of the damper plate is controlled by the draft controller switch to achieve a proper draft within design range. If draft is lost at any time, the controller moves the damper to the full open position and a loss-of-draft safety timing period commences. If draft is not re-established during this period, the system shuts off the fuel and locks out. When the call for heat is satisfied, the system closes the damper and is prepared for another operating cycle. All operating elements, both electronic and mechanical, are tested in a full operating cycle because operation of a subsequent cycle cannot commence unless the damper plate is returned to the fully closed position which also reduces heat loss during periods of non-use. A failure of any component locks the system out.

Furnace draft control system with electronic loss-of-draft timer

A pilot assembly includes a base having a cylindrical side wall which holds an electrode subassembly and glass preforms in place for fusing the glass to secure the electrode subassembly to the base. Prior to fusing, a spark electrode is assembled by inserting it into a metal clip receptacle held in a ceramic insulator body forming a part of the electrode subassembly. A pilot tip and orifice subassembly are secured to the base. Fusion of the glass and brazing of the metal including the high tension clip to bring it to spring temper for connection to a plugged wire are accomplished in a single step of heating. The pilot tip includes a locator member which holds the spark electrode in place during fusing and establishes the spark gap. It is removed after fusing. A connecting flange of a bracket is then positioned relative to the side wall of the base to achieve a desired angular disposition, axial orientation and height adjustment of the base relative to the bracket; and the bracket is welded to the side wall of the base. Thus, the same structural elements can be used for many different models of a gas pilot assembly without the need for special parts or process steps for manufacture.

Gas pilot assembly for universal application and method of making same

An electronic thermostat includes digital electronic apparatus for simulating heat anticipation so that in operation, the temperature of the room being heated or cooled does not exhibit excessive overshoot. A sensor generates a signal representative of temperature in the room. In a preferred embodiment, the system compares the temperature signal with a composite set point signal. The composite set point signal is generated by a data processor to effect the following system characteristics: (1) when the temperature signal remains constant and is equal to the set point, the system can cycle approximately six times an hour with a fifty percent duty cycle; (2) a relatively small change in temperature or set point will modify the duty cycle substantially; and (3) if the temperature and set point signals differ by more than a predetermined amount, the system will lock on or off, depending on which is greater.

Electronic thermostat with heat anticipation and control method

The illustrated embodiment is electronic. It includes circuitry for simulating heat anticipation so that in operation, the temperature of the room being heated or cooled does not exhibit excessive overshoot. A signal is generated representative of a desired set point, and another signal is generated representative of room temperature. An output signal, derived from a comparison circuit, is either ON or OFF. An integrator is reset each time the output signal is switched and generates a ramp voltage of increasing magnitude and having a polarity tending to reverse the state of the comparison circuit. The comparison circuit generates an ON signal when the set point signal is greater than the combined temperature and ramp signals; and it generates an OFF signal when the set point signal is less than the combined signals. The comparison circuit latches up once it has switched to avoid hunting or chatter.

Thermostat with simulated heat anticipation

A furnace ignition and draft control system includes a damper plate movable under control between a closed and an open position. When a call for heat signal is generated, a holding relay is actuated to energize a damper motor to open the damper provided the damper plate was closed when the signal was generated, otherwise the system will not operate. After the damper is run to the full open position and this is proved, a fuel control circuit is actuated to supply fuel to the furnace, and a trial-for-draft period is initiated. A draft controller energizes the damper motor to open the damper if draft is less than a first predetermined value and to close the damper if draft is greater than a second predetermined value. The predetermined draft values define a desired draft range in which the damper is not operated. If a draft greater than the second value is sensed within the trial period, the draft controller partially closes the damper to control the draft value within the desired draft range, otherwise the system locks out at the end of the trial period. If draft is lost at any time, the controller moves the damper to the open position and a loss-of-draft safety timing period commences. If draft is not reestablished during this period, the system shuts off the fuel and locks out. If the call for heat is satisfied, the system closes the damper and is prepared for another operating cycle, having tested the operativeness of all major components without failure. Any failure would have locked the system out.

Furnace ignition system with draft control and loss-of-draft protection

A control system for use with gas-fired appliance installations, such as a furnace, includes a switch responsive to normal draft levels in the vent stack. At the start of a heating cycle, and in the absence of draft, the switch permits a pre-draft enabling circuit to tentatively enable the furnace controller for a predetermined time. The controller opens a stack damper plate and actuates the ignition system and gas valves of the furnace. If draft is not established within the predetermined time, the pre-draft enabling circuit times out and the gas is shut off. If normal draft is sensed within the predetermined time, the draft responsive switch permits the furnace controller to be operated as long as the thermostat calls for heat. If, for any reason, draft subsequently stops, the control system re-cycles itself; and if draft is not re-established before the pre-draft enabling circuit times out, the system deactivates the furnace controller. The control system also includes a normally closed barometric damper, which is mounted in the vent stack and is responsive to both excessive positive pressure and to excessive draft (sub-ambient pressure) to open, and thereby neutralize the excessive positive pressure or draft.

Method and apparatus for controlling furnace

An humidistat has an element movable in response to ambient relative humidity operatively connected to a core of a linearly variable differential transformer for moving the core. The core is supported within a body portion of the transformer for minimal friction of movement relative to the body portion. The body portion has a primary winding and two secondary windings. An oscillator excites the primary winding to provide output signals from the secondary windings proportioned to movement of the core in the body portion and, therefore, indicative of the relative humidity sensed by the element.

Humidistat

A control arrangement for a heating system including a furnace having a fuel-fired burner apparatus and a vent stack with a motor driven damper plate pivotally mounted within the stack, includes a stack damper control circuit including first and second limit switches which permit energization of a drive motor in response to a request for heat, premitting the damper plate to be driven to an open position, and for energizing an interlock switch which prepares an energizing path for fuel supply valves of the system, the first limit switch being operated when the damper plate approaches the open position to complete the energizing path for the fuel supply valves prepared by the interlock switch, and the second limit switch deenergizing the motor when the damper plate is driven to the fully open position. The motor is reenergized at the end of the heating cycle to drive the damper plate to the closed position, and the second limit switch deenergizes the motor when the damper plate reaches the closed position.

Interlock arrangement for a stack damper control

A method and control arrangement for a heating system including solar heating apparatus and a conventional fuel-fired heating apparatus wherein heat load of the heating system and solar heating source capability are compared, and the heating system is switched to solar heating whenever the heating capability of the solar heating apparatus exceeds the heat load of the system, the heating system being switched to the conventional heating apparatus only when the heat load exceeds the heating capability of the solar heating apparatus. The control arrangement includes a first sensor which provides a first output indicative of heat load for the system as indicated by average fuel consumption by a burner of the conventional heating apparatus or the duty cycle of a thermostat of the system, a second sensor which provides a second output indicative of the temperature of a solar heated medium, and a controller which responds to the first and second outputs to provide heat for the system from the solar heated medium whenever possible. In one embodiment, the controller includes a differential temperature sensing device, and in a second embodiment, the controller includes a microprocessor system.

Method and control arrangement for a heating system including solar and

A stack damper control arrangement for use in a heating system including a furnace having a fuel-fired burner apparatus and a vent stack for conducting combustion products away from the burner apparatus and a damper plate pivotally mounted within the stack and movable between a fully open and a fully closed position, includes a reversible drive motor which is energizable in response to a request for heat to drive the damper plate to the open position, a first limit switch operated when the damper plate reaches the open position to effect the deenergization of the motor, the motor being reenergized at the end of the heating cycle to drive the damper plate to the closed position, and a second limit switch operated when the damper plate reaches the closed position to effect the deenergization of the motor. The damper control arrangement is described with reference to a heating system including a gas fired burner and redundant gas valves wherein operation of a first one of the gas valves is effected through operation of the first limit switch and thus is conditional upon the damper being fully open, and wherein the supply of fuel to the second valve is conditional upon the operation of the first valve.

Stack damper control arrangement

An anti-reset windup proportional plus integral controller connectable in a proportional control loop of a process control system includes a proportional amplifier circuit and an integrating amplifier circuit responsive to a command signal to provide proportional and integral signals, respectively, which are summed by a summing amplifier to provide a modified command signal having a proportional and an integral component. A signal comparator means compares the modified command with a pair of reference signals which define an output range for said summing amplifier and disables the integrating amplifier circuit, permitting the integrating amplifier circuit to unwind whenever the modified command signal is not within the output range.

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Goshen, IN, United States of America

Thomas E Hayes